This invention relates to a production method for ball support structures suitable for the use in ball joints, spherical bearings, etc.
An example of conventional ball support structures used in ball joints comprises a joint member or a ball support and a shaft provided with a ball at an end thereof. The joint member has a thin cylindrical portion projecting into one side of the joint member from around a recess formed for receiving the ball. The thin cylindrical portion is caulked to cover part of the ball after the ball is fitted on the recess so that the ball is prevented from being pulled out from the joint member. Another example of the ball support structure is disclosed in Japanese Utility-Model Laid-Open No. 57-113711/1982 in which a ball joint socket receives a ball of a ball stud, a ball seat is disposed on the ball of the ball stud, and then a part of the ball joint socket is caulked to press the ball seat on the ball, so that the ball is held by the ball joint socket and the ball seat.
In the former example of the conventional ball support structures, using the thin cylindrical portion for holding the ball, the cylindrical portion which is limited in the thickness is only covered on the ball. Therefore, the structure is weak in pulling-out strength and relatively large play occurs between the ball and the joint member receiving the ball when the ball is pulled from the joint member. In particular, when the ball support structure is used as a ball joint mechanism of piston and a connecting rod, a large pulling force acts on the ball support member every time the piston reciprocates. Therefore, the play between the ball and the ball support member increases according to the lapsed time of the operation.
In the latter example of the conventional ball support structures which employ the ball seats, there is left the problem that the number of structural parts increases, and the structure is complicated.